Nano Spray‐Dried Block Copolymer Nanoparticles and Their Transformation into Hybrid and Inorganic Nanoparticles

A novel combination of block copolymer (BCP) nano spray‐drying (NSD), solvent annealing, and selective metal oxide growth is utilized to create functional polymer nanoparticles, polymer‐metal‐oxide hybrid nanoparticles, and templated metal oxide nanoparticles with tunable composition, internal morphology, and porosity. NSD of BCPs from chloroform and toluene solutions results in porous and nonporous nanoparticles, respectively, with various degrees of phase separation. Further tuning of the nanoparticle internal morphology is performed by solvent annealing the spray‐dried particles with judicious choice of the nonsolvent dispersion medium and the surfactant, yielding assembly of both blocks at the surface of the nanoparticles. Finally, ZnO and Al₂O₃ are grown inside the polar blocks of phase‐ordered nanoparticles using a sequential infiltration synthesis method, in a post‐assembly process, resulting in hybrid BCP‐ZnO particles and BCP‐templated Al₂O₃ nanoparticles, as demonstrated by scanning transmission electron microscopy tomography. These structure engineering methods open new ways to direct and template functional nanoparticles.     

Metal Oxide Heterostructure Array via Spatially Controlled–Growth within Block Copolymer Templates

Nanofabrication is continuously searching for new methodologies to fabricate 3D nanostructures with 3D control over their chemical composition. A new approach for heterostructure nanorod array fabrication through spatially controlled–growth of multiple metal oxides within block copolymer (BCP) templates is presented. Selective growth of metal oxides within the cylindrical polymer domains of polystyrene‐block‐poly methyl methacrylate is performed using sequential infiltration synthesis (SIS). Tuning the diffusion of trimethyl aluminum and diethyl zinc organometallic precursors in the BCP film directs the growth of AlO_x and ZnO to different locations within the cylindrical BCP domains, in a single SIS process. BCP removal yields an AlO_x‐ZnO heterostructure nanorods array, as corroborated by 3D characterization with scanning transmission electron microscopy (STEM) tomography and a combination of STEM and energy‐dispersive X‐ray spectroscopy tomography. The strategy presented here will open up new routes for complex 3D nanostructure fabrication.     

Blood lymphocytes in infectious mononucleosis share the following characteristics with activated T cells: natural attachment, stable E rosetting and glucocorticoid sensitivity

Blood lymphocytes of infectious mononucleosis (IM) patients, unlike these obtained from healthy individuals, exhibit the following characteristics of activated T cells: (1) "stable" E rosette formation; (2) natural attachment to various human normal and malignant cells; (3) sensitivity in vitro to the lytic effect of glucocorticoids. Although the IM T cells attach in vitro to all the human cells tested, they kill only the EBV genome carrying targets. The possibility is discussed that some of the activated T cells in IM result from a non-specific activation elicited by the T cells responding specifically to the EBV associated antigens.     

Biologically Relevant Molecular Finite Automata

Bio-Molecular Computing (BMC) has been rapidly evolving as an independent field at the interface between computer science, mathematics, chemistry, and biology. Over the years, numerous architectures of autonomous molecular computing devices have been developed in the lab on the basis of opportunities offered by molecular biology techniques. This account focuses mainly on the realization of programmable DNA-based finite-state automata that can compute autonomously upon mixing all their components in solution.The main advantage of autonomous BMC devices over electronic computers arises from their ability to interact directly with biological systems and even with living organisms without any interface. Indeed, it has been demonstrated that appropriately designed computing machines can produce output signals in the form of a specific biological function via direct interaction with living cells. Additional topics are briefly included to point at interesting opportunities in the field and to describe some of the potential applications and extension of the basic concepts. These include logic evaluators and logic gates that operate in cells, applications in developmental biology, as well as chemical encoding and processing of alphanumeric information.     

Lysine synthesis and catabolism are coordinately regulated during tobacco seed development

The regulation of synthesis and accumulation of the essential amino acid lysine was studied in seeds of transgenic tobacco plants expressing, in a seed-specific manner, two feedback-insensitive bacterial enzymes: dihydrodipicolinate synthase (EC 4.2.1.52) and aspartate kinase (EC 2.7.2.4). High-level expression of the two bacterial enzymes resulted in only a slight increase in free lysine accumulation at intermediate stages of seed development, while free lysine declined to the low level of control plants toward maturity. To test whether enhanced catabolism may have contributed to the failure of free lysine to accumulate in seeds of transgenic plants, we analyzed the activity of lysine-ketoglutarate reductase (EC 1.5.1.7), an enzyme that catabolizes lysine into saccharopine. In both the control and the transgenic plants, the timing of appearance of lysine-ketoglutarate reductase activity correlated very closely with that of dihydrodipicolinate synthase activity, suggesting that lysine synthesis and catabolism were coordinately regulated during seed development. Notably, the activity of lysine-ketoglutarate reductase was significantly higher in seeds of the transgenic plants than in the controls. Coexpression of both bacterial enzymes in the same plant resulted in a significant increase in the proportions of lysine and threonine in seed albumins. Apparently, the normal low steady-state levels of free lysine and threonine in tobacco seeds may be rate limiting for the synthesis of seed proteins, which are relatively rich in these amino acids.     

Behavior state matching during interactions of preadolescent friends versus acquaintances.

Face-to-face interactions of 56 6th-grade friend and acquaintance pairs were videotaped, heart rate was recorded, and saliva cortisol was sampled. During interactions the friend dyads were more attentive, affectively positive, vocal, active, involved, relaxed, and playful, and their cortisol values suggested lower stress levels. They also spent more time together in mutually interested and animated states, and they assigned higher ratings to liking their interactions and interaction partners. Greater coherence in the friend pairs' behavior states and in the acquaintance pairs' vocal activity suggested that the friend pairs more often shared the same behavior state (e.g., playful), and the acquaintance pairs more often paid attention to each others' turn-taking signals, so that when one person talked, the other was silent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)